An outbreak of infections caused by non-typeable Haemophilus influenzae in an extended care facility

Nosocomial outbreaks of infection due to non-typeable Haemophilus influenzae (NTHi) are rarely described. There are a few published reports that suggest that elderly patients with underlying pulmonary disease are at risk and that person-to-person spread is key to disease transmission. During the summer months of 2005, we documented an outbreak of NTHi infections in a Veterans Affairs nursing home. Thirteen patients developed conjunctivitis or lower respiratory infection involving a beta-lactamase-negative biotype III NTHi isolate, with an indistinguishable SmaI macrorestriction pattern. Patients were elderly males usually with underlying cardiac and pulmonary disease. A case-control study failed to demonstrate any specific significant risk factor for NTHi infection and there was no evidence of spatial clustering of cases within the nursing home. A random throat culture survey involving nursing home patients during the outbreak showed that only one of 19 persons was colonized with NTHi. The outbreak concluded following appropriate treatment and an emphasis on universal and respiratory droplet precautions. All patients recovered and a specific inciting event for the outbreak was never defined. Literature review revealed a spectrum of responses to nosocomial NTHi infections and a lack of consensus regarding the infection control approach towards NTHi outbreaks.